IBM B50 manual in theDiagnostics Information for, 2-15, Step, Multiple Bus Systems

Step 1520-4

Either the power supply, the power switch, the system fan, or the system board is defective.

Exchange the FRUs that have not already been exchanged in the following order:

Power supply

Power switch

System fan

System board (See notes on page 2-1)

To test each FRU:

1.Unplug the power cord from the server.

2.Exchange one of the FRUs in the list.

3.Plug the power cord into the server.

4.Turn on the power.

Does the fan in the power supply turn on and the power LED come on and stay on?

NO	Reinstall the original FRU.
	Repeat this step until the defective FRU is identified or all the FRUs have
	been exchanged.
	If the symptom did not change and all the FRUs have been exchanged,
	call your service support person for assistance.
	If the symptom has changed, check for loose cards, cables, and obvious
	problems. If you do not find a problem, return to “Step 1520-1” on page
	2-13and follow the instructions for the new symptom.
YES	Go to "MAP 0410: Repair Checkout	" in theDiagnostics Information for
	Multiple Bus Systems.

Chapter 2. Maintenance Analysis Procedures (MAPs) 2-15